$ { \left[\begin{array}{rr}{-1} & {2} \\ {3} & {-1} \\ {2} & {1}\end{array}\right]-\left[\begin{array}{rr}{2} & {-2} \\ {-1} & {-1} \\ {2} & {2}\end{array}\right] = {?} } $
Solution: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}-{2} & {2}-{-2} \\ {3}-{-1} & {-1}-{-1} \\ {2}-{2} & {1}-{2}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{-3} & {4} \\ {4} & {0} \\ {0} & {-1}\end{array}\right]}$